The present disclosure relates generally to downhole well-logging tools and, more particularly, to wireless communication for downhole well-logging tools.
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present techniques, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
A variety of downhole tools are used to obtain wellbore measurements. In general, downhole tools include sensors to measure the parameters of the rock formation surrounding the wellbore. Some downhole tools may obtain wellbore measurements by emitting radiation into the surrounding rock formation and detecting radiation that returns to the tool. These nuclear downhole tools may emit radiation using radioisotope sources or electronic nuclear radiation generators.
A downhole tool string may house one or more downhole tools. Typically, the downhole tool string includes a data storage device and/or a controller (often collectively referred to as a recorder). Communication with the downhole tool string via the data storage device and/or the controller may require an electrical connection to certain communication ports in the downhole tool string. The design of these electrical connectors may be prohibited by a variety of factors. Among other things, the mechanical constraints of the pressure housing of the downhole tool string may prohibit the use of these electrical connectors. Certain government regulations, such as the European ATEX (ATmospheres EXplosibles) regulations, may also proscribe the use of such electrical connectors at a producing wellsite.
Given these constraints on wired communication, certain wireless communication approaches have been attempted. Even conventional wireless communication approaches, however, may not be effective in many common well-logging circumstances. In one approach, a sonic device such as a buzzer may be used to relay information between the downhole tool string and a human operator. The buzzer may communicate with the tool operator with a series of high-volume beeps of selected timing and duration. Though effective under some circumstances, the sonic buzzer may be difficult to hear on a typical rig floor, since an operating rig may have a number of very high-volume sound sources. Not only does external noise interfere, but the sound penetration through the typical downhole tool string housing may also be limited. Furthermore, the range of information that can be transferred through the sonic device or buzzer is minimal due to the inconsistency of sound communications in such an uncontrolled environment. Finally, the transmission of information is unidirectional in this approach—from the sound buzzer in the downhole tool string to the human operator—meaning this manner of communication cannot be used to reprogram the downhole tool string once it has been lowered into the well.
In another wireless communication technique, an optical communication port in the housing downhole tool string may communicate by sending and receiving light signals. Optical communication in this way may depend on a direct, unimpeded view of the optical communication port. Thus, communication may be effective when the downhole tool string is in plain view of an external optical transceiver. When the downhole tool string is deployed through a pressure riser of a well, however, conventional wireless optical communication may be precluded.